In recent years, energy-saving homes, stores, and buildings (hereinafter, collectively called “power consumer's facilities”) have been advocated to address concerns about an electric power shortage and to meet demands for environmental protection. Especially in summer and winter seasons when power demand is higher, each power consumer's facility sometimes consumes an amount of power that is greater than a power consumption (hereinafter, called “contract demand”) that has been settled by a contract between the power consumer's facility and an electric company. As a way to prevent the amount of power consumed from exceeding the contract demand by effectively saving energy, a power control system including a power control device (for example, Energy Management System: EMS) provided in each power consumer's facility to control load apparatuses used in the power consumer's facility, a decentralized power source installed in the power consumer's facility, and so forth is known. (Refer to Patent Literature 1, for example.)